1. Field of the Invention
The present invention relates to a charge pump system, especially refers to a charge pump system having function of voltage detection.
2. Description of the Prior Art
Charge pumps are widely used in electronic circuitry. Please refer to FIG. 1, FIG. 1 shows a prior art charge pump system 100. The charge pump system 100 includes a charge pump 14, an oscillator 16, a comparator 18, a first resistor 11 and a second resistor 12. The charge pump 14 is coupled to an input voltage VDD and receives signals from the oscillator 16 for providing an output voltage VOUT. The charge pump system 100 generates a second resistor voltage VR2 via a current flowing through the first resistor 11 and the second resistor 12 to control the operation of the oscillator 16 by comparing the second resistor voltage VR2 with a reference voltage Vref.
However, the first resistor 11 and the second resistor 12 may cause the charge pump system 100 to generate a leakage current, dropping and making the output voltage VOUT unstable. A common method for solving the above problems is to increase the resistance of the first resistor 11 and the second resistor 12. However, the increase of the resistance of the first resistor 11 and the second resistor 12 may cause delay to the output voltage VOUT. Thus the charge pump system 100 cannot achieve a desirable performance.